Substituted formamidines

ABSTRACT

SUBSTITUTED FORMAMIDINES OF THE FORMULA   CLNH(3-N)C-CO-N=CH-N(-R)-R&#39;&#39;   WHEREIN N IS A WHOLE NUMBER FROM 1 TO 3, INCLUSIVE, WHEREIN R AND R&#39;&#39; ARE LIKE OR UNLIKE AND ARE ALIPHATIC CONTAINING FROM 1 TO 4 CARBON ATOMS, INCLUSIVE, AND CONTAINING FROM 0 TO 3 CHLORO SUBSTITUENTS, INCLUSIVE. R&#39;&#39; CAN ALSO BE PHENYL OR MONOCHLORO- OR DICHLORO SUBSTITUTED PHENYL. THE COMPOUNDS EXHIBIT PRE-EMERGENT PHYTOCIDAL ACTIVITY.

United States Patent 01 fice 3,562,326 Patented Feb. 9, 1971 3,562,326SUBSTITUTED FORMAMIDINES Angelo John Speziale, Creve Coeur, and LowellR. Smith, Chesterfield, Mo., assignors to Monsanto Company, St. Louis,Mo., a corporation of Delaware No Drawing. Filed June 17, 1968, Ser. No.737,345 Int. Cl. C07d 103/44 U.S. Cl. 260561 7 Claims ABSTRACT OF THEDISCLOSURE Substituted formamidines of the formula This inventionrelates to new and useful substituted formamidines of the generalformula wherein n is a whole number from 1 to 3, inclusive, butpreferably 3, wherein R and R are like or unlike and are aliphaticcontaining from 1 to 4 carbon atoms, inclusive, and containing from to 3chloro substituents, inclusive, namely alkyl, alkenyl, chloroalkyl orchloroalkenyl, such as methyl, ethyl, propyl, butyl, allyl, butenyl,chloroethyl, dichloroethyl, chloropropyl, trichlorobutyl, chloroallyl,dichloroallyl, trichloroallyl, chlorobutenyl, dichlorobutenyl,trichlorobutenyl, and the various isomeric forms thereof. R can also bephenyl or monochloroor dichloro substituted phenyl. These compounds arereadily prepared by bringing together and reacting an isocyanate of thegeneral formula wherein n has the same significance as above with asubstantially equimolecular proportion of a formamide of the formulawherein R and R, respectively, have the same significance as above, inthe presence of an inert organic liquid or solvent in a fluid system,that is above the freezing point of the system up to and including theboiling point of the system.

As illustrative of the preparation of the compounds of this inventionbut not limitative thereof is the following:

EXAMPLE I To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser is charged approximately 3.65 parts byweight of dimethylformamide and approximately 44 parts by weight ofbenzene. While agitating the so-charged mass approximately 9.90 parts byWeight of a,ot,ot-trichloroacetyl isocyanate is slowly added and thereaction mass agitated for about one hour (During the addition of theisocyanate carbon dioxide evolved.) heated up to its boiling point, andthen refluxed for about one hour. Thereupon the mass is cooled and undervacuum stripped of benzene and other volatiles. The solid residue isthen taken up With a methylenechloride-hexane mixture andre-crystallized therefrom to give N,N-dimethyl-N-(a,a,a-trichloroacetyl)formamidine C13C-(JN=CHN(CH3)2 which melts at 5556 C.

EXAMPLE II To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser there is charged approximately 6.75 partsby weight of N-phenyl-N-methyl formamide, approximately 9.4 parts byweight of oc,ot,atrichloroacetyl isocyanate, and approximately 87 partsby weight of toluene. Thereupon the so-charged mass is refluxed forabout 16 hours. The mass is then cooled and stripped in vacuo of tolueneand other volatiles. The solid residue is then taken up with a methylenechloride-hexane mixture containing charcoal and re-crystallizedtherefrom to give N-phenyl-N-methyl-N'-(a,a,a-trichloroacetyl)formamidine which melts at 6l62 C.

In like manner to the above described procedural operations butemploying the appropriate chloro substituted acetyl isocyanate and theappropriate N,N-disubstituted formamide the following formamidines areprepared:

N,N-diethyl-N'-(a,a,a-trichloroacetyl) formamidine,N,N-di-n-propyl-N-(a,a,ot-trichloroacetyl) formamidine,N,N-diallyl-N'-(a,a,u-trichloroacetyl) formamidine,N,N-din-butyl-N'-(a,a,ot-trichloroacetyl) formamidine, N-methyl-N-(2-chloroallyl) -N'- (a,a,a-trichlor0acety1) formamidine,N-methyl-N-isopropyl-N-(a,a,a-trichloroacetyl) formamidine,N-phenyl-N-ethyl-N'-(a,a,a-trichloroacetyl) formamidine,N-phenyl-N-allyl-N-(a,a,u-trichloroacetyl) formamidine,N-phenyl-N-isopropyl-N'-(a,a,a-trichloroacetyl) formamidine, N-(4-chloropheny1) -N-methyl-N'-( u,ot,a-trichloroacetyl) formamidine,N,N-dimethyl-N-(a,u,a-trichloroacetyl) formamidine,N,N-diallyl-N'-(a,ot-dichloroacetyl) formamidine,N,N-di-n-propyl-N'-(a,a-dichloroacetyl) formamidine, N-(2,3,3-trichloroallyl -N-methyl-N'- (a,a-dichloroacetyl) formamidine,N-isopropyl-N-methy1-N'-(u,ot-dichloroacetyl) formamidine,N-phenyl-N-methyl-N'-(a,a-dichloroacetyl) formamidine,N-phenyl-N-is0propyl-N'-(a,a-dichloroacetyl) formamidine,N,N-dimethyl-N'-(u-chloroacetyl) formamidine,N,N-di(2,3-dichloroallyl)-N'-(a-chloroacetyl) formamidine,N-isopropyl-N-methyl-N'-(a-chloroacetyl) formamidine,N-isobutyl-N-ethyl-N'-(ot-chloroacetyl) formamidine,N-phenyl-N-methyl-N'-(a-chloroacetyl) formamidine,N-phenyl-N-isopropyl-N'-(a-chloroacetyl) formamidine,N-phenyl-N-isopropyl-N-(oi-chloroacetyl) formamidine,

etc.

The methods by which the aforedescribed compounds of this invention areisolated will vary slightly with the reactants employed and the productproduced. Further purification by selective solvent extraction or byabsorptive agents such as activated carbon or clays can precede theremoval of the inert organic liquid (or solvent) when the latter isemployed. Additionally an inert organic solvent can be added to and inthe purification by absorptive agents. However, in that the products arephytocidally active they are generally satisfactory for phytocidalpurposes without further purification.

In the procedural operations set forth herein before in addition tobenzene and toluene, the various xylenes can be used, or mixturesthereof as can hexane, heptane, octane, etc. and mixtures thereof. Thereaction is preferably conducted at a temperature above about 70 C. toabout 200 C. under atmospheric pressure in a dry atmosphere until thecarbon dioxide by-product ceases to evolve from the reaction mass.

The compounds of this invention are uniquely useful in inhibiting thegrowth of noxious gasses (i.e. narrow leaf plants) and noxious broadleaf weed plants exclusive of broad leaf crop plants prior to theirrespective emergence from soil or other growth media by treating saidsoil or other growth media with an effective growth inhibiting amountthereof. To illustrate their unique pre-emergent phytocidal activity,but not limitative thereof, is the following:

Seeds of a variety of several different plants itemized hereinafter eachrepresenting a principal botanical species are planted in each ofseveral aluminum pans by scattering them randomly over the surface of agood grade of top soil treated with 0.05% by weight based thereon of aresinous polyelectrolyte soil conditioner which was compacted to a depthof from the top of each pan. The so-seeded respective pans are thencovered with /8" of the aforesaid prepared soil mixture and therespective pans levelled.

The levelled surface of the soil in each pan, exclusive of the controlpan, is then sprayed with an aliquot of acetone containing the followingcompounds each at the rate of 25 pounds per acre, which compounds areidentified by code as follows:

Compound N,N-dimethyl-N'-(a,a,u-trichloroacetyl) formamidine AN-phenyl-N-methyl-N'- a,ec,a-trichloroacetyl) formamidine BN,N-dimethyl-N- (Z-chlorophenyl) formamidine C The respective pans areplaced in a sand bench and /2 of water added to the bench. The soilabsorbs moisture through perforations in the bottom of the respectivepans until the soil surface of each is about one-half moist, by whichtime the excess water in the sand bench is drained oif. The remainingsoil surface in each pan is moistened by capillary action.

Fourteen days later in the greenhouse under ordinary conditions ofsunlight and watering after the said application of each of theafore-itemized compounds the results are observed and recorded. Thenumber of plants which emerged from the soil are counted and convertedto a phytocidal rating by means of a fixed scale based on averagepercent emergence. (Emergence rates are established for all new seedlots and periodic checks run on old seed in current use.) The scale usedis as follows:

CONVERSION SCALE (Number of plants emerging) The relative emergencevalue of the respective aforeitemized compounds with respect to theirphytocidal effects on each plant is indicated by a number as follows:

0=No inhibition.

1 Slight inhibition. 2=Moderate inhibition. 3: Severe inhibition.

TABLE I Plant/comp ound A B O Contro1 (Grasses):

Wild oat 3 3 0 0 Brome grass. 3 3 O 0 Rye grass 3 3 0 0 Foxtail 3 3 0 0Grab grass. 3 3 0 0 Sorghum 3 3 0 0 (Broad leaf):

Radish O 0 0 0 Sugar beet 0 0 0 0 Pigwced 3 3 3 0 Tomato 0 0 0 0 Asfurther illustrative of the unique pre-emergent phytocidal activity, butnot limited thereof, is the followmg:

Seeds of a variety of several different plants itemized hereinafter eachrepresenting a principal botanical species are planted in each ofseveral aluminum pans by scattering them randomly over the surface of agood grade of top soil treated with 0.05% by weight based thereon of aresinous polyelectrolyte soil conditioner which was compacted to a depthof from the top of each pan. The so-seeded respective pans are thencovered with of the aforesaid prepared soil mixture having intimatelymixed therewith an aliquot of acetone containing the following itemizedcompounds each in an amount providing a rate of 5 pounds per acre, whichcompounds are identified by code as follows, and the respective panslevelled:

N,N-dimethyl-N'-(3,4-dichlorophenyl) formamidine F The respective pansare placed in a said bench and /2" of water added to the bench. The soilabsorbs moisture through perforations in the bottom of the respectivepans until the soil surface of each is about one-half moist, by whichtime the excess water in the sand bench is drained off. The remainingsoil surface in each pan is moistened by capillary action.

Fourteen days later in the greenhouse under ordinary conditions ofsunlight and watering after the said application of each of theafore-itemized compounds the results are observed and recorded. Thenumber of plants which emerged from the soil are counted and convertedto a phytocidal rating by means of a fixed scale based on averagepercent emergence. (Emergence rates are established for all new seedlots and periodic checks run on old seed in current use.) The scale usedis as follows:

CONVE RSION SCALE Seed lot percent emergence (control) (Number of plantsemerging) The relative emergence value of the respective aforeitemizedcompounds with respect to their phytocidal effects on each plant isindicated by a number as follows:

=No inhibition.

1=Slight inhibition.

2=Moderate inhibition.

3=Severe inhibition.

In addition Compound A did not inhibit the emergence of corn or cottonin this evaluation.

From the foregoing pre-emergent phytocidal evaluation data it isapparent that the N,N-disubstituted-N'-(chloro substituted acetyl)formamidines of this invention are effective preemergence herbicides.Valuable pro-emergent phytocidal effects will be observed byapplications of small amounts, for example, as low as 0.1 lb. of activecomponent per acre as well as higher concentrations, for example, 30lbs. per acre. The preferred range of application for pro-emergentphyocidal purposes is from about 1 to 15 lbs. per acre.

It will be apparent that different effects can be obtained by modifyingthe method of use. For this reason an essential part of this inventionis the formulation thereof so as to permit a uniform predeterminedapplication of the new phytocides to soil or other growth media so as toproduce the desired tffect. By proper selection and proportioning of thevarious conditioning agents either liquid or solid formulations can beprepared, and so as to adapt the new phytocide for achieving the desiredresult with any conventional device for treating the surface orsub-surface of the soil or other growth media.

Although the compounds of this invention are useful per se in cntrollinga wide variety of plant growth in the pro-emergent state, it ispreferable that they be supplied to the plant growing medium in adispsersed form in a suitable extending agent.

In the instant specification and appended claims it is to be understoodthat the term dispersed is used in its widest possible sense. When it issaid that the compound of this invention are dispersed, it means thatthe particles thereof can be molecular in size and held in true solutionin a suitable organic solvent. It means further that the particles canbe colloidal in size and distributed throughout a liquid phase in theform of suspensions or emulsions or in the form of particles held insuspension by wetting agent. The term dispersed also means that theparticles can be mixed with and distributed throughout a solid carrierproviding a mixture in particulate form e.g. pellets, granules, powders,or dusts.

The exact concentration of the compounds of this invention employed incombatting or controlling noxious vegetation can vary considerablyprovided the required dosage (i.e. phytotoxic amount) thereof issupplied to the plant growing medium. From a practical point of view,the manufacturer must supply the agriculturist with a low-costconcentrate or spray base or particulate solid base in such form, thatby merely mixing with water or solid extender (eg., powdered clay ortalc) or other lowcost material available to the agriculturist at thepoint of use, he will have an easily prepared phytocidal spray orparticulate solid. In such a concentrate composition, a compound of thisinvention generally will be present in a concentration of 5 to 95percent by weight, the residue being any one or more of the well-knownphytocidal adjuvants, such as the various surface active agents (e.g.detergents, a soap or other emulsifying or wetting agent), surfaceactive clays, solvents, diluents, carrier media, adhesives, spreadingagents, humectants, and the like.

There are a large number of organic liquids which can be used for thepreparation of solutions, suspensions or emulsions of the compounds ofthis invention. For example, isopropyl ether, acetone, methyl ethylketone, dioxane, cyclohexanone, carbon tetrachloride, ethylenedichloride, tetrachloroethane, hexane, heptane and like higher liquidalkanes, hydrogenate naphthalenes, solvent naphtha, benzene, toluene,xylene, petroleum fractions (e.g. those boiling almost entirely under400 F. and having a flash point above about F, particularly kerosene),mineral oils and the like.

The compounds of this invention are preferably applied to the plantgrowing medium in the form of emulsions or suspensions. Emulsions orsuspensions are prepared by dispersing a compound of this inventioneither per se or in the form of an organic solution thereof in waterwith the aid of a Water-soluble surfactant. The term surfactant asemployed here in the appended claims is used as in Volume II ofSchwartz, Perry and Berchs Surface Active Agents and Detergents (1958,Interscience Publishers, Inc., New York) in place of the expressionemulsifying agent, to connote generically the various emulsifyingagents, dispersing agents, wetting agents and spreading agents that areadapted to be admixed with the active compounds of this invention inorder to secure better wetting and spreading of the new phytocidalingredient in the water vehicle or carrier in which it is insolublethrough lowering the surface tension of the water (see also FrearChemistry of Insecticides, Fungicides and Herbicides," second edition,1948, page 280). These surfactants include the well-known capillaryactive substances which may be anion-active (or anionic), or, andpreferably, non-ionizing (or non-ionic) which are described in detail inVolume I and II of Schwartz, Perry and Berchs Surface Active Agents andDetergents, (1958, Interscience Publishers, Inc., New York) and also inthe November 1947 issue of Chemical Industries (pages 811-824) in anarticle entitled Synthetic Detergents by John W. McCutcheon and also inthe July, August, September, and October, 1952 issues of Soap andSanitary Chemicals under the title Synthetic Detergents. The disclosuresof these articles with respect to surfactants, i.e. the anion-active andnon-ionizing capillary active substances are incorporated in thisspecification by reference in order to avoid unnecessary enlargement ofthis specification. The preferred surfactants are the water-solublenon-ionic surface-active agents set forth in US. 2,846,398 (issued Aug.4, 1958).

The compounds of this invention can be dispersed by suitable methods(e.g., tumbling or grinding) in solid extending agents either of organicor inorganic nature and applied to the plant growing medium inparticulate form. Such solid materials include for example, tricalciumphosphate, calcium carbonate, kaoline, bole, kieselguhr, talc,bentonite, fullers earth, pyrophillite, diatomaceous earth, calcinedmagnesia, volcanic ash, sulfur and the like inorganic solid materialsand include for example, such materials of organic nature as powderedcork, powdered wood, and powdered walnut shells. The preferred solidcarriers are the adsorbent clays, e.g. attapulgus clay. These mixturescan be used for phytocidal purposes in the dry form or by addition ofwater-soluble surfactants or wetting agents the dry particulate solidscan be rendered wettable by water so as to obtain stable aqueousdispersions or suspensions suitable for use as sprays.

In all of the forms described above the dispersions can be providedready for use in combatting noxious vegetation or they can be providedin a concentrated form suitable for mixing with or dispersing in otherextending agents. As illustrative of a particularly useful concentrateis an intimate mixture of a compound of this invention with awater-soluble non-ionic surfactant which lowers the surface tension ofwater in the weight proportions of 0.1 to 15 parts of surfactant withsufficient of a compound of this invention to make 100 parts by weight.Such a concentrate is particularly adapted to be made into a spray forcombatting various forms of noxious vegetation by the addition of waterthereto. As illustrative of such a concentrate is an intimate mixture of95 parts by weight of N,N-dimethyl-N- a,a,a-trichloroacetyl formamidineand parts by weight of a water-soluble nonionic surfactant such aspolyoxyethylene derivative of sorbitan monolaurate.

Another useful concentrate adapted to be made into a spray forcombatting noxious vegetation is a solution (preferably as concentratedas possible) of a compound of this invention in an organic solventtherefor. The said liquid concentrate preferably contains dissolvedtherein a minor amount (e.g. 0.5 to 10 percent by weight of the weightof the new phytocidal agent) of a surfactant (or emulsifying agent),which surfactant is water-soluble. As illustrative of such a concentrateis a solution of N,N-dimethyl-N-(a,ot,u-trichloroacetyl) formamidine inacetone which solution contains dissolved therein a water-solublenon-ionic surfactant.

Of the surfactants aforementioned in preparing the various emulsifiable,wettable or dispersible compositions or concentrates of this invention,the non-ionic surfactants are preferred. Of the non-ionic surfactantsthe particularly preferred are the water-soluble polyoxyethylenederivatives of alkylphenols (particularly isooctylphenol) and thewater-soluble polyoxyethylene derivatives of the mono-higher fatty acidesters of sorbitan respectively containing to 30 moles of ethylene oxideper mole of sorbitan mono-ester of alkylphenol.

The compounds of this invention can also be advantageously employed incombination with other pesticides, including, for example, fungicides,nematocides, bactericides, and insecticides. In this manner it ispossible to obtain mixtures which are effective against a wide varietyof pests and other forms of noxious life.

While this invention has been described with respect to certainembodiments, it is to be understood that it is not so limited and thatvariations and modifications thereof obvious to those skilled in the artcan be made without departing from the spirit and scope thereof.

8 What is claimed is 1. A substituted formamidine of the general formulawherein n is a whole number from 1 to 3, inclusive, wherein R isaliphatic containing from O to 3 chloro substituents, inclusive, andcontaining from 1 to 4 carbon atoms, inclusive, and is selected from thegroup consisting of alkyl, alkenyl, chloroalkyl and chloroalkenyl, andwherein R is selected from the group consisting of (a) aliphaticcontaining from 0 to 3 chloro substituents, inclusive, and containingfrom 1 to 4 carbon atoms, inclusive, and is selected from the groupconsisting of alkyl, alkenyl, chloroalkyl and chloroalkenyl, and (b)phenyl, and phenyl substituted by from 1 to 2 chloro substituents,inclusive.

2. A compound of claim 1 wherein n is 3 and wherein R and R,respectively, are selected from the group con sisting of like and unlikealkyl containing from 1 to 4 carbon atoms.

3. A compound of claim 1 wherein n is 3, wherein R is alkyl containingfrom 1 to 4 carbon atoms, inclusive, and wherein R is phenyl.

4. A compound of claim 2 wherein R and R, respec tively, are methyl.

5. A compound of claim 2 wherein R and R, respectively, are allyl.

6. A compound of claim 3 wherein R is methyl and wherein R is phenyl.

7. A compound of claim 3 wherein R is isopropyl and wherein R is phenyl.

References Cited Schwartz et al.: Surface Active Agents and Detergents,1958, Interscience Publishers, New York.

ALEX MAZEL, Primary Examiner R. V. RUSH, Assistant Examiner US. Cl. X.R.7l1l8; 260-562

